SAN FRANCISCO — Eden Adams, 65, is ready to upgrade after using her iPhone for about three years.

The schoolteacher from Fremont, Calif., had looked at her daughter’s Samsung Electronics smartphone, which has a larger screen, and considered buying the Korean manufacturer’s device before learning of Apple’s plans to roll out new iPhones with bigger displays.

‘‘My daughter’s is easier to read; the quality of her pictures are really good too,’’ she said, adding that she hopes to buy a new iPhone soon. ‘‘I am even tempted to switch, but I don’t want to learn too many new things.’’

Adams and others at or near retirement age could prove to be a customer category that will help make the iPhone 6 another bestseller. Apple unveiled Tuesday two new iPhone models: one with a 4.7-inch screen and another with a 5.5-inch display. The larger model now sits squarely in the same league as similar oversized models made popular by rivals such as Samsung and LG Electronics.

After pioneering the smartphone market, Apple is moving away from its focus on smaller screens. While bigger displays make it easier for a younger crowd to read digital books, play games, or watch movies, the large screens also let people who need reading glasses boost the size of the font and images on their smartphones without sacrificing screen real estate.

Advertisement

Slightly more than half of consumers planning to buy a smartphone will opt for a larger device, according to a survey conducted earlier this year by Accenture.

‘‘Samsung did sort of create this ‘phablet’ market, but I think that doesn’t mean that Apple wouldn’t benefit greatly by moving into this direction,’’ said J.P. Gownder, an analyst at Forrester, referring to products that are an amalgamation of phones and tablets. ‘‘The average age is getting older and clearly visual acuity declines in that situation.’’

Advertisement

The 4.7-inch iPhone 6, which will have rounded edges and a thinner frame than earlier models, will cost $199 to $399 with a two-year contract in the United States, while the larger 6 Plus is priced at $299 to $499. The devices are set to ship on Sept. 19 in a limited number of countries.

At 5.5 diagonal inches, the heftiest iPhone is more than one-third larger than the last model, in terms of screen area. It’s also larger than one of Samsung’s leading devices, the Galaxy S5, which has a 5.1-inch screen. The iPhone 6 Plus is just slightly smaller than the Samsung Note 3, which is 5.7 inches. Other phones made by LG and HTC Corp. are also 5 inches or larger.

Mel Gurney, 58, a retired physician in Santa Rosa, Calif., said he’s looking forward to replacing his 5S iPhone with the new 5.5-inch version.

“When something comes through on my iPhone that I really need to read, I got to run around the house looking for my reading glasses,’’ he said. ‘‘Vision is everything. If you can’t see it, it doesn’t do you much good.’’